Apparatus for tightening and locking nuts on bolts



Nov. 25, 1969 R. T. ALLSOP 3,479,714

APPARATUS FOR TIGHTENING AND LOCKING NUTS ON BOLTS Filed Dec. 22, 1966 I5 Sheets-Sheet 1 Ill Fig.

zozna luvemoe'. @oaem'weuoe ALLsoP (W61 mm A em Nov. 25, 1969 R. T.ALLSOP 3,479,714

APPARATUS FOR 'I'IGHTENING AND LOCKING NUTS ON BOLTS Filed Dec. 22, 19665 Sheets-Sheet 2 luvarror; Roam freuoa PrLLSoP 6% KM Mar Nov. 25, 1969R. T. ALLSOP 3,479,714

APPARATUS FOR TIGHTENING AND LOCKING NUTS 0N BOLTS Filed Dec. 22, 1966 5Sheets-Sheet 5 F/gfi I8 47 +48 Fig. 8.

(mvm flowkr Tea/0c HLLSOP 1 war 4 Nov. 25, 1969 R. T. ALLSOP 3,479,714

' APPARATUS FOR TIGHTENING AND LOCKING NUTS ON BOLTS Filed Dec. 22, 19665 Sheets-Sheet 4 lMvem-o e: 4203M Tevol mm P w Kwvk' (mm Nov. 25, 1969 RT. ALLSOP 3,479,714

APPARATUS FOR TIGH'IENING AND LOCKING mm on BOLTS Filed Dec. 22, 1966 5Sheets-Sheet 5 Fllg. /O.

United States Patent 3,479,714 APPARATUS FOR TIGHTENING AND LOCKING NUTSON BOLTS Robert T. Allsop, Storton, near Stourbridge, England, assignorto G.K.N. Screws & Fasteners Limited, Birmingham, Warwick, England, aBritish company Filed Dec. 22, 1966, Ser. No. 603,910 Claims priority,application Great Britain, Dec. 24, 1965, 54,851/ 65 Int. Cl. B23p 19/08U.S. Cl. 29200 9 Claims ABSTRACT OF THE DISCLOSURE A tool for tighteningand locking a nut on a bolt having a substantially cylindrical body, aspindle extending axially within the body, a motor for rotating thespindle connected to one end thereof, a nut engaging wrench memberconnected to the other end of the spindle and also slidable axially onthis end of the spindle, a pneumatically operated impact piston slidablymounted upon the spindle within the body and having a tubular sleeveprojecting from its forward face for delivering an axially directedimpact to the rear of the wrench member and a deforming tool mountedwithin the wrench member and having forwardly extending projections toengage and deform the end face of a nut which is engaged by the wrenchmember.

There are at present many forms of lock nuts which are adapted forapplication to the threaded shank of a bolt in a nut and bolt assembly.The expression nut and bolt assembly is intended to cover various caseswhere two or more members are secured together by means of a bolt, orthe like, having an externally threaded shank which is engaged by a nut.Whilst in most cases the bolt will be of conventional form having a headat one end, there are also cases in which the threaded shank is in theform of a tud secured in some way in one of the mem bers, and hence theexpression bolt as used herein, is intended to cover also such cases.

A great many different forms of lock nuts used hitherto rely for theiraction upon exerting an increased gripping force on the thread of thebolt and there are various examples of nuts in which this done by someform or other of distortion or displacement of the thread of the nut, sothat at localised positions it has an increased grip on the threadedshank of the bolt such as to resist any tendency for the nut to slackenoff during use when the nut and bolt assembly may be subject tovibration and other forces tending to loosen the nut.

However, even if a lock nut is used, the nut and bolt assembly is notefficient if, at the initial application, the nut is not tightened downa sufficient extent to achieve tension in the bolt shank, and it hasbecome recognised in practice that, for maximum efliciency in boltusage, the nut must 'be tightened down until a predetermined minimumtension is reached, and preferably exceeded, in the bolt shank. Unlesssuch minimum tension is achieved during tightening then even theslightest degree of slackening of the nut may mean that all tension willdisappear from the bolt shank, and although the lock nut may beperfectly efiicient to resist coming completely off the end of the bolt,the position has already been reached where a bolted assembly is now nolonger efiicient because there is no tension in the bolt, and hence noclamping force holding the members together.

Such lock nuts, as referred to above, which act by applying an increasedfrictional grip, will require more operator-torque than a conventionalnut when being used, as the operator has got to overcome the increased3,479,714 Patented Nov. 25, 1969 resistance due to the locking meanswhen tightening the nut down. This extra torque required can frequentlymislead an operator into thinking that the desired torque has beenachieved to get tension in the bolt shank and thus bolted assemblies canbe made with such lock nuts which are not tightened to a suflicientextent to achieve maximum efliciency in the bolted connection. Also,such lock nuts are generally always more expensive than ordinary nuts.

The object of this invention is to provide new or improved apparatus fortightening a nut in a nut and bolt assembly and locking the nut on thebolt.

In one form, the apparatus may comprise a tool having a nut engagingwrench member, power means for rotating said wrench member to applytorque to a nut engaged therewith, :an impact member slidable in thetool in the axial direction of the wrench member, a deforming toolassociated with the wrench member and positioned to engage the end faceof the nut adjacent the free end of th bolt and power means fordelivering an impact to said impact member to cause it to drive thedeforming tool into engagement with said end face of the nut.

In another form, the apparatus may comprise a nutengaging wrench member,power means for rotating said wrench member, one or more impact membersmounted for reciprocating movement radially of the axis of the wrenchmember and means for causing reciprocating movement of said impactmember or members to cause it, or each one, to deliver one or moreradial impacts to the wall of the nut.

In this form of apparatus there may be a nut-engaging wrench memberhaving mounted thereon one or more impact members, each of which ismounted in the wrench member for reciprocating sliding movement indirections radially of the nut axis, a rotary driving member forrotating the wrench member to apply rotary torque to the nut, clutchmeans for transmitting rotary motion from said driving member to theWrench member, which clutch means is rendered inoperative whenresistance to rotation of the wrench member reaches a predeterminedvalue, and means whereby rotation of said driving member relative tosaid socket member causes reciprocating movement of the impact member ormembers.

The invention is illustrated in the accompanying diagrammatic drawingswherein:

FIGURE 1 is a part-sectioned view in side elevation of one form of toolfor carrying out the invention.

FIGURE 2 is a sectioned view showing the end of the tool on enlargedscale.

FIGURE 3 is an end view looking from the right in FIGURE 2.

FIGURE 4 is a view of the end of the tool as in FIG- URE 1 with a nutengaged therein prior to application to a bolt.

FIGURE 5 is a view showing the. stage reached in tightening the nutprior to application of impact.

FIGURE 6 is a view showing the stage subsequent to FIGURE 5 when theimpact has been delivered.

FIGURE 7 is a plan view of the nut after the locking operation has beenperformed.

FIGURE 8 is a section through the nut shown in FIG- URE 7.

FIGURE 9 is a diagrammatic section of the operative end of another formof tool for carrying out the method according to the invention.

FIGURE 10 is an end-on view of this tool.

Referring to FIGURE 1, the tool shown therein comprises a body which isin three main parts, there being a hand grip part 10, a centre part 11,and a nose part 12, and an air motor of generally known form, and notshown, is housed within the hand grip part 10 and has a driving shaft 13which is drivingly connected to a spindle 14 extending axially throughcentre part 11 and nose part 12 of the gun and at its extreme end beingformed with a portion of square cross section engaging slidably in anaxial passage of corresponding cross section in a sleeve 16, whichsleeve is rotatably mounted within the bore of the nose part 12 and isalso capable of axial sliding movement therein.

The sleeve 17 has at its forward end an axial extension 17 of reducedcross section passing rotatably and slidably through an aperture in theend wall of the nose part of the tool and there is mounted on the outerend of this part 17 a wrench member 18 which is generally in the form ofa sleeve detachably secured to the part 17 by a retaining spring ring19.

The forward free end of the wrench member 18 is provided with a nutengaging socket 20 which may be of hexagonal form or, as shown, oftwelve-sided form, and within the wrench member 18, to the rear of thenut engaging socket 20, there is a recess in which is mounted thedeforming tool 21 held in position by a retaining spring 22.

The construction of the deforming tool 21 is shown in more detail anddescribed hereinafter with reference to other figures of the drawings.

The centre part 11 of the tool is of cylindrical form and provides acylinder 23 within which there is mounted, for reciprocating slidingmovement, a piston 24 formed integrally upon a tubular member 25 whichis slidably mounted upon the spindle 14 and the piston 24 has a suitablesealing ring 26 engaging with the internal wall of the cylinder 23.

Mounted within the centre part 11 and fixed therein, is a block 27having an axial opening 28 extending therethrough and of larger diameterthan the diameter of the tubular sleeve 25 which therefore passes freelythrough the block 27 and on its forward face the block 27 is providedwith a raised annular sealing lip 29 which is engaged by a resilientsealing disc 30 fixed in the rearward end of the piston 24 when thispiston is in its retracted position at the right hand of the cylinder23, as shown in FIGURE 1. Suitable sealing rings 31 are provided in thehand grip part and the nose part 12 of the tool around the tubularsleeve 25 so as to seal and make airtight the space within the cylinder23 and also the air chamber 32 to the rear of the piston 24.

Air under pressure is admitted to the air chamber 32 from a suitablesupply of compressed air which would be connected by a flexible hose tothe opening 33 and likewise air under pressure can be admitted into thecylinder 23 through the opening 34 also adapted to be connected to aflexible hose for supplying air under pressure, whilst with suitable andgenerally known form of valve mechanism, not shown, the openings 33 and34 can also act as exhaust ports to allow air to be exhausted from thechamber 32 and cylinder 23 at the appropriate times.

Although not shown, there would also be suitable connection to supplyair to, and exahust air from the air motor in the hand grip part 10.

Also in the block 27 there is provided an exhaust port 35 communicatingwith an exhaust opening 36 which may be connected to a suitable tube orpipe for a purpose hereinafter referred to.

The following brief description of the operation of the tool is givenwith reference to FIGURE 1, although a more detailed description isgiven later herein with reference to FIGURES 2 to 8, which show in moredetail the various stages of the operation of tightening a nut upon abolt and locking the nut in position.

For rotating the wrench member 18 to run the nut on to the bolt andtighten it down, the air motor driving shaft 13 rotates the spindle 14and this rotates the wrench member 18 to apply the desired torque to anut engaged in the socket 20. When a predetermined torque has beenapplied, generally determined by a known form of slipping clutch,

within the tool, the air control is operated to admit air. underpressure to the chamber 32 and this acts upon the face of the sealingdisc until the pressure builds up to sulficient value to leak past theseal between sealing lip 29 and sealing disc 30, so that instantaneouslythe air pressure acts upon the whole of the operative surface of thepiston 24, causing rapid acceleration of the piston from right to leftin FIGURE 1, thus driving the tubular sleeve 25 forwardly so that theforward end 37 of this sleeve, which acts as the impact member strikesthe rear face 38 of the sleeve 16 and thereby delivers an axial impactvia sleeve 16 and wrench member 18 to the deforming tool 21 to apply thedesired deformation, as hereinafter described, to the nut engaged in thesocket 20.

The air controls are then operated to admit air under pressure via theport 34 to the other left hand face of the piston, as seen in FIGURE 1,to move the piston back to its original position at the right hand orrear end of cylinder 23. The purpose of the exhaust port is to allowescape of air from the annular chamber 39 and prevent any build-up ofair pressure which might prevent the sealing disc 30 from seating firmagainst the cylinder 29 when the piston is in its initial position atthe one end of the cylinder.

When the piston is performing its return movement the port 33 is actingas an exhaust port for exhaust of air from the chamber 32.

With reference now to FIGURE 2, the nose part of the tool body isindicated at 12, the wrench member at 18, the nut-engaging socket at 20and the deformation tool at 21 and it will be seen that the deformationtool 21 has three equiangularly spaced projections 40 around theperiphery of the axial hole 41 in the tool. This hole 41 communicatesaxially with a hole 42 in the part 17 and it will be seen that theforward end of the part 17 bears against an internal annular shoulder43, in the wrench member 18, whereby the axial impact from impact member37 is transmitted to the deformation tool 21.

Referring now to FIGURES 4, 5 and 6, there is shown the stages in theapplication of a nut 44 to the threaded end 45 of a bolt 46 for holdingtogether two members 47 and 48 in a nut and bolt assembly, and thisassembly has a washer 49 placed about the bolt so as to be underneaththe nut when this is applied. FIGURE 4 shows the nut 44 engaged in thesocket 20 of the wrench member 18 prior to application to the bolt.

The controls of the tool are operated to cause rotation of the wrenchmember 18, thus running the nut 44 down the threaded end 45 of the boltuntil the stage of FIG- URE 5 is reached when the tightening of the nuthas proceeded to the extent that the torque applied by the wrench member18 reaches a predetermined magnitude upon which the known form ofslipping clutch mechanism in the tool comes into operation and rotationof the wrench member 18 ceases so that an indication is obtained that atorque of predetermined magnitude has been reached and thus thepredetermined minimum tension achieved (or exceeded) in the bolt shank.

At this stage the controls of the tool are further operated to operatethe impact member 37 (FIG. 1) and deliver an impact to the annularshoulder 43 of the wrench member 18 and thus to the deformation tool 21so that this advances relative to the nut 44 and the three projections40 form indentations in the end face of the nut (see FIG. 6) asexplained more clearly hereinafter with reference to FIGURES 7 and 8.

As the effect of the impact causes the wrench member 18 and deformingtool 21 to move (in the direction left to right FIG. 6) relative to thenut 44, the end face 50 of the wrench member 18 impacts against thewasher 49 and this avoids any indentation being caused on the outersurface of member 47.

To provide for this movement axially of the wrench member 18, the socket20 is of such axial depth that when the nut is engaged therein (see FIG.4 and FIG. 5),

the one end face of the nut projects slightly beyond the end face 50 ofthe wrench member 18.

Referring now to FIGURES 7 and 8, the impact of the three projections 40of the deforming tool produce three corresponding indentations 51 in theend face of the nut 44, and as seen in FIGURE 8, these indentationsdeform the thread at localised positions immediately adjacent this oneend face of the nut so as to force these portions of the thread radiallyinwards into firm frictional engagement with the thread of the bolt soas to achieve the desired locking action.

With reference now to FIGURES 9 and 10, which show diagrammatically partof another tool for carrying out the invention, the nut is shown at 110engaged in the tool, and the form of nut preferred for use with thistool has, as shown, a generally conventional nut body 110 of hexagonalform provided at one end with an axially extending collar 111 which isof substantially reduced wall thickness and is of circularcross-section.

The tool comprises a nut-engaging wrench member 112 which has an axialopening therethrough which is of hexagonal cross-section at its forwardend 113 so as to have non-rotative engagement with the hexagonal body ofthe nut.

The wrench member 112 is mounted concentrically within an annual body114 which has a rearwardly axially extending part 115 which is connectedto, or forms part of, the rotary driving shaft of a power-operated toolwhich may for example be in the form of any of the generally known typesof power-operated nut runners and needs no further description.

The wrench member 112 is provided with a plurality of impact members116, each of which is mounted slidably in a radially extending passage117 in the wrench member, such passage 117 having an enlarged part 118at its radially outer end in which the enlarged head 119 of the impactmember slidably engages, and each enlarged part 118 having locatedtherein a coil spring 120 acting under the head 119 to urge the impactmember 116 in the radially outwards direction.

At its inner end each impact member 116 has an operative swaging end 121of substantially conical form and when the nut is engaged in the wrenchmember these ends 121 are adapted to engage the reduced collar 111 ofthe nut.

The inner wall 122 of the annular body 114 of the driving member isformed at equi-angularly spaced positions with a number of radiallyinwardly projecting lobes or cam surfaces 123 and, as will be observedfrom FIGURE 10, each of the impact members 116 are urged by theirsprings 120 radially outwards so as to maintain the heads 119 of theimpact members in engagement with the said inner wall 122 of the annularbody of the driving member.

In the example shown, there are four impact members 116 and four camsurfaces 123.

At the front end of the tool a suitable form of retaining plate 124 isprovided to hold the wrench member in position.

In operating with this form of tool, the nut engaged in the wrenchmember is applied to the end of the bolt and the driving member 115rotated to run the nut along the thread of the bolt and intoengagement-with the abutment surface (eg the member 47 or Washer 49 inFIG. 4). During this action the lobes 123 will be in the positionindicated in FIGURE and will act upon the heads of the impact members soas to form aclutch means to transmit the rotary driving torque fromdriving member 115 to the wrench member and thus cause rotation of thenut until such time as the torsional resistance to rotation of the nutreaches a predetermined value corresponding to a desired tension beingachieved in the bolt shank, whereupon the wrench member 112 becomesstationary and the resistance of the springs 120 is overcome so that thedriving member 115 continues to rotate about the axis of the nutrelative to the stationary wrench member. As will be observed from theconsideration of FIGURE 10, this results in the lobes or cams 123applying a series of radially directed impacts to the impact members116, causing these to be driven radially inwards to operate upon thecollar 11 of the nut and deform portions of the internal thread of thenut into gripping engagement with the co-operating threads of the bolt,the extent of the inwards movement of the impact members being indicatedin dotted lines in FIGURE 10.

What I claim then is:

1. Apparatus for tightening and locking a nut on a bolt comprising atool having a nut engaging wrench member, power means for rotating saidwrench member to apply torque to a nut engaged therewith, an impactmember slidable in the tool in the axial direction of the wrench member,a deforming tool associated with the wrench member and positioned toengage the end face of the nut adjacent the free end of the bolt andpower means for delivering an impact to said impact member to cause itto drive the deforming tool into'engagement with said end face of thenut.

2. A tool according to claim 1 having a body, a spindle extendingaxially within said body, power means within the body drivinglyconnected to one end of said spindle for rotating same, the other end ofsaid spindle being drivingly connected to the wrench member for rotatingsame and the wrench member being slidably axially relative to said otherend of the spindle, the deforming tool being connected to the wrenchmember and the impact member being arranged within the body of the toolso as to deliver the impact to the wrench member.

3. A tool according to claim 2 wherein the impact member comprises apiston reciprocably mounted in a cylinder formed in the tool body, thepiston being slidable axially upon the said spindle and having extendingfrom its forward face, which is the face nearest the wrench member, atubular sleeve also slidable upon said spindle and constituting theimpact member, there being suitable ports in the body of the tool forsupply to, and exhaust from, the cylinder, of air under pressure foroperating said piston.

4. A tool according to claim 3, in the form of a gun having a hand grippart in which is mounted an air-operated motor for rotating saidspindle, a centre part which comprises the said cylinder and a forwardnose part in the forward end of which there is rotatably and axially,slidably mounted a sleeve having a driving connection with the forwardend of the spindle and being slidable relative thereto, the wrenchmember carrying the deforming tool being mounted on the forward end ofsaid sleeve, the arrangement being that the impact member strikes therearward end of said sleeve when the piston is operated.

5. A tool according to claim 4 wherein the wrench is in the form of asleeve having an opening extending axially inwards from its forward end,the mouth of the opening being formed as a nut-engaging socket and thedeforming tool being mounted in the said opening to the rear of saidsocket, said deforming tool having a plurality of forwardly extendingprojections adapted to deform the end face of a nut around the peripheryof the threaded opening therein.

6. Apparatus for tightening and locking a nut on a bolt in the form of atool comprising a nut-engaging wrench member, power means for rotatingsaid Wrench member, one or more impact members mounted for reciprocatingmovement radially of the axis of the wrench member and means for causingreciprocating movement of said impact member or members to cause it, oreach one, to deliver one or more radial impacts to the wall of the nut.

7. A tool according to claim 6 comprising a nut-engaging wrench memberhaving mounted thereon one or more impact members, the or each of whichis mounted in the wrench member for reciprocating sliding movement indirections radially of the nut axis, a rotary driving member forrotating the Wrench member to apply rotary torque to the nut, clutchmeans for transmitting rotary motion from said driving member to theWrench member, which clutch means is rendered inoperative whenresistance to rotation of the wrench member reaches a predeterminedvalue, and means whereby rotation of said driving member relative tosaid socket member causes reciprocating movement of the impact member ormembers.

8. A tool according to claim 7 wherein the wrench member is ofcylindrical form and has an axial opening therethrough, the forward endof which forms a nutengaging socket, and the wrench member is mountedconcentrically within an annular body (constituting the said drivingmember) having a rearwardly extending, power driven, shaft for rotatingthe annular body about the axis of the wrench member, the wrench memberbeing provided with a plurality of impact members, slidably mounted inradially extending passages formed in the wrench member and the innerwall of the annular body having a plurality of inwardly projecting camsurfaces adapted to act upon the radially outward ends of the impactmembers to drive these radially inwardly when the annular body rotatesrelatively to the wrench member.

9. A tool according to claim 8 wherein each of the impact members isurged outwardly by spring means and engagement between said cam surfacesand the impact members against the resistance of the spring meansconstitutes the clutch means for transmitting rotary motion from theannular body to the wrench member, the resistance of the spring meansbeing overcome when the torque applied by the Wrench member to the nutreaches a predetermined value so as to permit relative rotation betweenthe annular body and the wrench member.

References Cited UNITED STATES PATENTS 1,925,714 9/1933 Crist 81l02,438,744 3/1948 Flynn 2924O X 2,538,343 l/1951 Van Winkle 81-102,943,335 7/1960 Daniel et al. 10-155 2,960,082 12/1960 Skidmore 81---102,974,406 3/ 1961 Vilmerding 29211 3,322,005 5/1967 Neuschotz 813 THOMASH. EAGER, Primary Examiner US. Cl. X.R.

